2026/04/09 by Renata Callegari Ferrari, ivan reyna-llorens · 1 voice
Agricultural and Biological Sciences · Biochemistry, Genetics and Molecular Biology · #Light effects on plants #Photosynthetic Processes and Mechanisms #Plant nutrient uptake and metabolism
paper · doi:10.1093/jxb/erag161
openalex publication_date 2026/04/09 · openalex created_date 2026/04/13 · openalex updated_date 2026/08/01
Plants have evolved carbon-concentrating mechanisms (CCMs) to optimize carbon fixation under environmental conditions that increase photorespiratory and transpiration rates. C4 and Crassulacean acid metabolism (CAM) photosynthesis are the two most widespread CCM examples across land plants and were typically considered to be incompatible due to biochemical, anatomical, evolutionary, and regulatory characteristics. However, Portulaca oleracea (purslane) was the first reported case to challenge this assumption >40 years ago. Although it remains one of the most characterized C4-CAM species, many aspects of this dual system are still unresolved. This expert view summarizes recent advances in understanding C4-CAM integration in Portulaca, highlighting key genomic, transcriptomic, biochemical, and physiological insights, and outlines the most pressing questions about the functioning and evolution of this combined CCM. Future directions for explaining how these convergent pathways emerged in the same lineage include functional studies on key regulatory elements, spatially resolved analyses for protein distribution and metabolic fluxes across leaves, an updated phylogeny of the family, and the integration of molecular and physiological data. So far, it is evident that expressing a weak CAM cycle in a C4 crop might be possible and could entail increased survival, possibly contributing to higher productivity in a future with climate change.